@Yannick_Nierop In the first image are you trying to have HubSpot send a webhook to itself? In the second photo I wasn't able to see the actual body of the post call. I want to make sure you have formatted the body correctly so HubSpot can read it properly. Here are the docs for the example of the body.

@Yannick_Nierop You most likely can't just send a webhook to HubSpot as the data won't be formatted properly. Which is why I was asking to see the body of the webhook to verify that. You will need a proxy server to catch the webhook and format the JSON in a way HubSpot can read it and then hit our APIs with the correctly formatted code.